Tappets

ABSTRACT

A tappet assembly including a hollow cylindrical tappet housing a roller assembly carried by a pin, the pin having extending portions beyond the side faces of the roller and the tappet assembly including a bridge piece having leg portions, which bear upon the pin. The force is transmitted from a cam acting upon the roller assembly to the bridge piece by way of the roller assembly, the extending portions of the pin and the leg portions of the bridge piece. The tappet housing serving only to locate the bridge piece and roller and to guide the movement of same under the action of the cam.

[H] 9 2 51 All Inventor Ronald Phillips Northolt, England Appl. No. 2,921 Filed Jan. 14, 1970 Patented Dec. 21, 1971 Assignee Simms Group Research and Development Limited London, England Priority Jan. 23, 1969 Great Britain 3,754/69 TAPPETS 7 Claims, 3 Drawing Figs.

US. Cl 123/9048, 123/905 l 74/569 Int. Cl F0ll 1/14, F l 6h 53/06 Field of Search 123/90 [56] References Cited UNITED STATES PATENTS 1,023,565 4/1912 Herbert 123/90 X 1,061,700 5/1913 Steinbecker..... 74/569 1,835,622 12/1931 Willgoos l l l23/90 2,735,313 2/1956 Dickson 74/569 Primary ExaminerAl Lawrence Smith Attorney- Holman & Stern ABSTRACT: A tappet assembly including a hollow cylindrical tappet housing a roller assembly carried by a pin, the pin having extending portions beyond the side faces of the roller and the tappet assembly including a bridge piece having leg portions, which bear upon the pin. The force is transmitted from a cam acting upon the roller assembly to the bridge piece by way of the roller assembly, the extending portions of the pin and the leg portions of the bridge piece. The tappet housing serving only to locate the bridge piece and roller and to guide the movement ofsame under the action of the cam.

PATENTED new m RamlhNVENTOR [lurm ATTQQNEYS TAPPETS This invention relates to tappet assemblies for use in highspeed reciprocating mechanisms the assemblies being of the kind comprising a tappet body which defines a bearing surface for cooperation with a complementary bearing surface defined in a housing for the mechanism, the assembly also including a roller for cooperation with the surface of a rotary cam and the assembly also defining a surface against which bears a member arranged to be operated by the cam through the intermediary of the tappet assembly.

In known tappet assemblies of the kind specified the tappet body has been formed from relatively heavy material with the result that when included in a reciprocating mechanism operating at high speed, the inertia forces due to the weight of the tappet assembly have been high.

The object of the invention is to provide a tappet assembly of the kind specified having a lower weight than known assemblies of the same size.

According to the invention a tappet assembly of the kind specified is characterized in that the roller is mounted upon a pin extending beyond the ends of the roller, the pin being located within a hollow tappet housing formed from relatively light material, the periphery of the housing defining said bearing surface, there being provided within the housing a bridgepiece which defines the surface for abutment with said member, said bridgepiece having leg portions which engage the extending portions of the pin, the force being transmitted from the roller to the surface on the bridge piece by way of the extending portions of the pin and said leg portions.

In the accompany drawings:

FIG. 1 is a part sectional side elevation of one example of a tappet assembly in accordance with the invention,

FIG. 2 is a view similar to FIG. 1 taken at right angles to FIG. 1 and FIG. 3 is a plan view of the tappet assembly of FIG. 1.

With reference to the drawings there is shown a reciprocating mechanism which includes a tappet assembly 9 slidable within a bore 8 defined in a housing 7 for the mechanism.

The tappet assembly includes a roller assembly 10 which comprises an outer annular roller member 14 rotatably mounted about a sleeve 13 which is carried by a pin having end portions extending beyond the roller member. The roller member together with the sleeve and the pin are formed from steel and the roller member 14 in use, engages with the cam surface of a rotary cam 6 located within the housing.

The tappet assembly also includes a hollow cylindrical tappet housing 12 which is formed of relatively light material and the outer surface of the housing defines a bearing surface for cooperation with the bearing surface defined by the wall of the bore 8. Adjacent its lower end the tappet housing 12 is provided with diametrically disposed apertures into which the end portions of the pin extend and at its lower end the tappet housing has an inwardly directed flange 21. The flange 21 defines an opening through which the roller member 14 extends, and portion of the flange bear against the end surfaces of the roller member and sleeve to locate same.

Within the tappet housing there is positioned a bridgepiece 11 having curved end faces which cooperate with the inner surface of the tappet housing. The bridgepiece is provided with depending leg portions 17, 18 disposed on opposite sides of the roller member 14 and which bear upon flats 19,20 formed on the extending portions respectively of the pin 15. The bridgepiece is retained within the tappet housing by means of a circlip 22. Moreover, the bridgepiece defines a surface 5 which in use, bears against a member 4 forming part of the mechanism and the bridgepiece is formed from steel.

In use, as the cam 6 rotates the member 4 by the action thereof and the force applied to the member is transmitted from the cam by way of the roller member 14, the sleeve 13, the pin 15 and the bridgepiece 11. These parts are formed from steel and are thus able to withstand the load involved. The tappet housing 12 is only required to locate the various parts of the tappet assembly and to guide the axial movement within the bore. Conveniently the tappet housing is formed from aluminum.

A tappet as herein described when constructed from steel and aluminum weights 0.45 kilograms whereas a conventional tappet of comparable size weights 0.65 kilograms.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

l. A tappet assembly for use in a high-speed reciprocating mechanism, the assembly comprising a hollow tappet housing the periphery of which defines a bearing surface for cooperation with a complementary bearing surface defined in a body mounting the mechanism, a roller mounted on the tappet housing for cooperation with a rotary cam to effect reciprocation of the housing, a pin about which the roller is mounted, extending end portions on the pin, opposed apertures formed in the tappet housing into which said extending end portions of the pin extend, flats formed on said extending end portions of the pins, a bridgepiece located within the tappet housing, said bridgepiece defining a surface for abutment with a member required to be reciprocated by the cam, and leg portions on the bridgepiece, said leg portions engaging with the flats on the extending end portions of the pin, whereby the force is transmitted from the roller to the surface on the bridgepiece by way of the extending portions of the pin and said leg portions.

2. A tappet assembly as claimed in claim 1 in which the extending portions of said pin are provided with flats against which said leg portion of the bridgepiece bear.

3. A tappet assembly as claimed in claim 2 in which the end portions of said extending portions of the pin extend within apertures formed in said tappet housing.

4. A tappet assembly as claimed in claim I in which said housing is of hollow cylindrical form, an inwardly extending flange at the end of the housing adjacent the roller, said flange bearing against the end faces of the roller to provide location of the roller within the housing.

5. A tappet assembly as claimed in claim 4 in which the end faces of the bridgepiece are shaped for cooperation with the internal surface of the tappet housing.

6. A tappet assembly as claimed in claim 5 including a circlip engaged within a groove formed in the internal surface of a tappet housing, said cirelip acting to retain the bridgepiece within the housing.

7. A tappet assembly as claimed in claim 6 in which the roller comprises an annular member rotatably mounted about a sleeve carried by the pin. 

1. A tappet assembly for use in a high-speed reciprocating mechanism, the assembly comprising a hollow tappet housing the periphery of which defines a bearing surface for cooperation with a complementary bearing surface defined in a body mounting the mechanism, a roller mounted on the tappet housing for cooperation with a rotary cam to effect reciprocation of the housing, a pin about which the roller is mounted, extending end portions on the pin, opposed apertures formed in the tappet housing into which said extending end portions of the pin extend, flats formed on said extending end portions of the pins, a bridgepiece located within the tappet housing, said bridgepiece defining a surface for abutment with a member required to be reciprocated by the cam, and leg portions on the bridgepiece, said leg portions engaging with the flats on the extending end portions of the pin, whereby the force is transmitted from the roller to the surface on the bridgepiece by way of the extending portions of the pin and said leg portions.
 2. A tappet assembly as claimed in claim 1 in which the extending portions of said pin are provided with flats against which said leg portion of the bridgepiece bear.
 3. A tappet assembly as claimed in claim 2 in which the end portions of said extending portions of the pin extend within apertures formed in said tappet housing.
 4. A tappet assembly as claimed in claim 1 in which said housing is of hollow cylindrical form, an inwardly extending flange at the end of the housing adjacent the roller, said flange bearing against the end faces of the roller to provide location of the roller within the housing.
 5. A tappet assembly as claimed in claim 4 in which the end faces of the bridgepiece are shaped for cooperation with the internal surface of the tappet housing.
 6. A tappet assembly as claimed in claim 5 including a circlip engaged within a groove formed in the internal surface of a tappet housing, said circlip acting to retain the bridgepiece within the housing.
 7. A tappet assembly as claimed in claim 6 in which the roller comprises an annular member rotatably mounted about a sleeve carried by the pin. 